Ignition systems



Sept. 1, 1964 A. GURVIZ I r 3,146,771

IGNITION SYSTEMS Filed March 19, 1962 2 Sheets-Sheet 1 Fly. 26

F 2 C //v I/EAIFO/P AA 555/0 9 VIM/Z p 1964 A. GURVIZ 3,146,771

IGNITION SYSTEMS Filed March 19, 1962 2 Sheets-Sheet 2 m m4 1 U I United States Patent 3,146,771 IGNITION SYSTEMS Alessio Gurviz, Via Fontana 18, Milan, Italy Filed Mar. 19, 1962, Ser. No. 180,689 Claims priority, application Italy Mar. 22, 1%1 6 Claims. (Cl. 123-448) This invention relates to an automatic electronic ignition advance control device for internal combustion engines.

The combustible mixture in the cylinders of an internal combustion engine is normally ignited during a part of the piston stroke preceding the top dead centre position, during the compression stroke. If the engine is to perform satisfactorily, the ignition advance must not stay the same but must be arranged to vary with engine speed v in accordance with a pattern based on the characteristics of the engine. Ignition advance is usually measured in degrees of crankshaft rotation, has a reduced value at low engine speeds, and increases as engine speed rises.

In conventional ignition systems where sparking is produced by a contact breaker being opened by a cam driven off the crankshaft, ignition advance is varied by means of a centrifugal governor counterweighted by opposing springs. Accurately calibrated springs must therefore be provided and the calibration thereof must not vary in the course of time. Wear of the contact breaker operating shoe and of the contact breaker contact points also leads in time to unwanted variation of the ignition advance.

This invention obviates contact breakers, contact breaker cams and centrifugal governors and provides an ignition advance control which does not vary in time. More particularly, the invention covers an ignition advance control system comprising a group of two alternators which are magnetically independent of one another and which are mechanically coupled with one another and with the shaft of the internal combustion engine and which are electrically interconnected through the agency of electrical components having a non-linear response to voltage or frequency, the connection between the two alternators being such that their respective output voltages are out of phase with one another, while the non-linear characteristics of the non-linear electrical components are such that the phase of the output voltage of the group of alternators at a pair of output terminals of the system varies in dependence upon the speed of the engine shaft. As used herein, non-linear component means a component wherein the ratio of the voltage or frequency applied thereacross to the current flow therethrough is not constant.

For a better understanding of the invention and to show how the same may be carried into effect, reference may now be made to the accompanying drawings wherein:

FIG. 1 illustrates a circuit diagram of one embodiment of the system according to the invention;

FIG. 1a is a diagrammatic view of one of the cornpotents shown in FIG. 1 and illustrates details thereof;

FIG. 1b is a diagrammatic view of another of the components shown in FIG. 1 and illustrates in details thereof;

FIGS. 2a to 2 are diagrams showing the operation of the system shown in FIG. 1;

FIG. 3 illustrates a circuit diagram of a second embodiment of the system according to the invention, and

FIG. 4 illustrates a circuit diagram of a third embodiment of the system according to the invention.

Referring first to FIG. 1, a shaft 1 is driven by a crankshaft of an internal combustion engine through some appropriate form of transmission (not shown), and two alternators 2, 3 are coupled with the shaft 1. The outputs of the two alternators 2, 3 are connected in series with one another. Shunted across the output of alternator 2 is a component 4 which varies non-linearly with voltage 3,14%,771 Patented Sept. 1, 1964 and which can take the form of a varistor or of a Zener diode or the like. In the example shown in FIG. 1a, non-linear component 4 comprises two seleniuum rectifiers 4a and 4b which are push-pull connected in parallel and operate on the forward current. Connected in series with the output of alternator 3 is an non-linear component 5 similar to the component 4. In the example shown in FIG. lb, non-linear component 5 comprises two Zener diodes 5c and 5d which are series connected in opposition to each other and have a smoothing resistor 52 connected in parallel therewith. Two linear resistors 6, 7 complete the circuit. The same operates as follows: The alternator 2 is so connected to the alternator 3 that the output voltage of alternator 2 lags by on the output voltage of alternator 3. At low engine speeds the output voltage of alternator 2 has the pattern shown in FIG. 2a, whereas, because of the non-linear component 5, the output voltage of alternator 3 at low speeds is as shown in FIG. 2b. More specifically, at low engine speeds the output voltage of alternator 2 is comparatively low and when applied across component 4 is unable to cause that component to draw current. Therefore the voltage across the output terminals of the system shown in FIG. 1 has asine wave form like that shown in FIG. 2a for alternator 2. Furthermore, at the same low engine speeds the low voltage generated by alternator 3 is unable to cause component 5 to conduct with the exception of the voltage peaks. Therefore, the voltage across load resistor 7 has the wave form shown in FIG. 2!). Thus, the voltage across the output terminals of the system shown in FIG. 1 is the sum of the voltages shown in FIGS. 2a and 2b and has the form shown in FIG. 20. Assuming that the phase shift between the two voltages is invariable, the sum of the two output voltages at low speeds is a curve as shown in FIG. 2c. As will be apparent, the curve shown in FIG. 2c leads by 12 on the curve shown in FIG. 2a. If such a voltage is used to control the ignition timing in an internal combustion engine and if 0 denotes the time of ignition in the absence of any advance, it will be apparent that at low engine speeds the system according to the invention provides a 12 ignition advance.

The output voltages of the alternators rise with increasing engine speed. The output voltage of alternator 2 is limited by the non-linear component 4 and has the pattern shown in FIG. 2d, whereas the output voltage of alternator 3 increases with the square root of engine speed and is as shown in FIG. 22. More specifically, with increasing engine speed an increase in voltage across component 4 beyond a predetermined level causes cornponent 4 toconduct a current of such magnitude that a voltage drop is developed across resistor 6 which prevents the voltage across component 4 from rising according to a sine wave form. Therefore, the voltage peaks are clipped by component 4- and a wave form is obtained across the output terminals of the system shown in FIG. 1 like that shown in FIG. 2d. Furthermore, at increased engine speed the voltage generated by alternator 3 causes component 5 to conduct so that a voltage is developed across resistor 7 having the wave form shown in FIG. 2e. Such voltage lacks the sine wave form because of the conductive characteristic of component 5 which distorts the sine wave form. Thus, the voltage across the output terminals of ,the system shown in FIG. 1 is the sum of the voltages shown in FIGS. 2d and 2e and has the form shown in FIG. 2f. Assuming that the phase shift between the two voltages does not vary, the sum thereof has the pattern shown in FIG. 2. It will be apparent that, if this voltage is used to control ignition advance in an internal combustion engine, it will advance the spark by 45. A comparison between the curves shown in FIGS. 20 and 2 will show that the system according to the invention can provide an ignition advance variation of 33 as be tween low and high engine speeds.

If the phases of the alternators are appropriately adjusted relatively to one another and to the engine shaft and if the characteristics of the non-linear components are appropriately chosen, the phase of the output voltage at zero value thereof can be arranged to coincide with the required advance.

The characteristics of the non-linear components can be adjusted by the provision in series or parallel with them of linear resistors, such as the resistors 6, 7 shown in FIG. 1.

In the embodiment illustrated in FIG. 3, the alternators are connected in parallel instead of in series with one another, 'but in other respects operation is exactly as for the system shown in FIG. 1. It is to be understood that the components 4 and 5 in FIG. 3 are similar in all .respects to the components 4 and 5, respectively, in

FIGURE 1.

The invention also covers the use of elements which vary non-linearly With frequency instead of with voltage. In the system illustrated in FIG. 4, the voltage delivered by the alternator 2 lags on the voltage delivered by the alternator 3. At low engine speeds an inductance 8 which is in series with the output of the alternator 2 forms a low impedance, since the voltage generated by the alternator is of a low frequency; consequently, there is substantially no limitation of the output voltage. A condenser 9 in series with the alternator 3 forms a high impedance at low speeds, the voltage generated by the alternator 3 being at a low frequency, and so the output voltage of the alternator 3 is very low. The sum of the two voltages has substantially the phase of the alternator 2. At high speeds the values of the impedences are reversed, with the result that the output voltage of the alternator 3 tends to predominate. The phase of the sum of the two voltages shifts accordingly.

Although some embodiments of the invention have been described, many variations and modifications can, of course, be made Without departing from the scope of the invention.

I claim:

. 1. In an automatic electronic ignition advance control system for internal combustion engines, said system having a pair of output terminals, in combination, two alternators which are magnetically independent of one another and are mechanically coupled to one another and to the shaft of the internal combustion engine, said alternator-s I having output terminals which are electrically series connected and their operation being timed so that the output voltages of said alternators are out of phase to one another, afirst electricalcomponent connected between one output terminal of one of said alternators and one output terminal of said system, said first electrical component being adapted to conduct a current which varies nonlinearly with the voltage across said first conponent, a second electrical component connected across the terminals of the other of said alternators in series with a first resistance, one of said terminals of the said other of said alternators serving as the other output terminal of said system, said second electrical component being adapted to conduct a current which varies non-linearly with the voltage across said component, and a second resistance connected between the junction point ofsaid second electrical component and said first resistance and said one terminal to said system. 7

2. In an automatic electronic ignition advance control system for internal combustion engines, said system having a pair of output terminals, in combination, two alterd nators which are magnetically independent of one another and are mechanically coupled to one another and to the shaft of the internal combustion engine, said alternators having output terminals which are electrically parallel connected and their operation being timed so that the output voltages of said alternators are out of phase to one another, a first electrical component connected between one output terminal of one of said alternators and one output terminal of said system, said first electrical component being adapted to conduct a current which varies non-linearly with the voltage across said first component, a second electrical component connected across the terminals of the other of said alternators in series with a first resistance, the other output terminal of the said one adapted to conduct a current which varies non-linearly with the voltage across said second component, and a second resistance connected between the junction point of said second electrical component and said first resistance and said one terminal of said system.

3. In an automatic electronic ignition advance control system for internal combustion engines, said system having a pair of output terminals, in combination, two alternators which are magnetically independent of one another and are mechanically coupled to one another and to the shaft of the internal combustion engine, said alternators having output terminals which are electrically parallel connected and their operation being timed so that the output voltages of said alternators are out of phase to one another, a first electrical component connected between one terminal of one of said alternators and one output terminal of said system, said first electrical component being adapted to conduct a current which varies non-linearly with the frequency of the voltage across said varies non-linearly with the frequency of the voltage across said second electrical component, the other terminals of said one alternator and said other alternator being electrically connected to the other output terminal of said system.

4. An automatic electronic ignition advance control system for internal combustion engines as claimed in claim 2, wherein said first electrical component includes two series connected opposite Zener diodes having a smoothing resistance connected in parallel thereto and said second electrical component includes two push-pull connected selenium rectifiers operating on the forward current.

5. An automatic electronic ignition advance control system for internal combustion engines as claimed in claim 1, wherein said first electrical component includes two series connected opposite Zener diodes having a smoothing resistance connected in parallel thereto and said second electrical component includes .two push-pull connected selenium rectifiers operating on the forward current.

6. An automatic electronic ignition advance control system for internal combustion engines as claimed in claim 1 '3, wherein said first electrical component includes a con- References Cited in the file of this patent FOREIGN PATENTS Germany Nov. 24, 1943 Great Britain Feb. 22, 1961 

1. IN AN AUTOMATIC ELECTRONIC IGNITION ADVANCE CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINES, SAID SYSTEM HAVING A PAIR OF OUTPUT TERMINALS, IN COMBINATION, TWO ALTERNATORS WHICH ARE MAGNETICALLY INDEPENDENT OF ONE ANOTHER AND ARE MECHANICALLY COUPLED TO ONE ANOTHER AND TO THE SHAFT OF THE INTERNAL COMBUSTION ENGINE, SAID ALTERNATORS HAVING OUTPUT TERMINALS WHICH ARE ELECTRICALLY SERIES CONNECTED AND THEIR OPERATION BEING TIMED SO THAT THE OUTPUT VOLTAGES OF SAID ALTERNATORS ARE OUT OF PHASE TO ONE ANOTHER, A FIRST ELECTRICAL COMPONENT CONNECTED BETWEEN ONE OUTPUT TERMINAL OF ONE OF SAID ALTERNATORS AND ONE OUTPUT TERMINAL OF SAID SYSTEM, SAID FIRST ELECTRICAL COMPONENT BEING ADAPTED TO CONDUCT A CURRENT WHICH VARIES NONLINEARLY WITH THE VOLTAGE ACROSS SAID FIRST CONPONENT, A SECOND ELECTRICAL COMPONENT CONNECTED ACROSS THE TERMINALS OF THE OTHER OF SAID ALTERNATORS IN SERIES WITH A FIRST RESISTANCE, ONE OF SAID TERMINALS OF THE SAID OTHER OF SAID ALTERNATORS SERVING AS THE OTHER OUTPUT TERMINAL OF SAID SYSTEM, SAID SECOND ELECTRICAL COMPONENT BEING ADAPTED TO CONDUCT A CURRENT WHICH VARIES NON-LINEARLY WITH THE VOLTAGE ACROSS SAID COMPONENT, AND A SECOND RESISTANCE CONNECTED BETWEEN THE JUNCTION POINT OF SAID SECOND ELECTRICAL COMPONENT AND SAID FIRST RESISTANCE AND SAID ONE TERMINAL TO SAID SYSTEM. 